Samsiah Sulaiman | University of Wollongong (original) (raw)

Papers by Samsiah Sulaiman

Teknik Spektroskopi Inframerah Transformasi Fourier (FJIR) digunakan dalam kajian ini untuk membu... more Teknik Spektroskopi Inframerah Transformasi Fourier (FJIR) digunakan dalam kajian ini untuk membuat pencirian ke atas dua sampel cat iaitu cat kayu dan cat simen. Objektif kajian ini adalah untuk mengalisis persarnaan dan perbezaan bagi cat kayu dan cat simen. Spektrum bagi kedua-dua cat ini dikumpul dengan menggunakan kaedah FTIR dengan perisian OMNIC buatan Syarikat Thermo-Nicolet Corporation, Amerika Syarikat. Peratus pemancaran (percent transmittance) %T melawan nombor gelombang dalam unit cm⁻¹ diplot pada spektrum kedua-dua cat. Daripada spektrum yang diperolehi, kumpulan berfungsi dan struktur ikatan molekul dapat dikenal pasti. Parameter yang dititik beratkan dalam kajian ini adalah frekuensi (cm), keamatan (kuat, sederhana, atau kuat), dan bentuk (lebar atau tajam). Kumpulan berfungsi yang dapat dikesan dalam larutan cat simen antaranya ialah alkobol dengan regangan O-H dan C-O, asid karboksilik O-H, alkana C-H, alkena C=C, sebatian karbonil dengan regangan C-O, Amina C-N dan alkil balida C-F. Larutan cat kayu juga mempunyai kumpulan berfungsi yang sarna seperti cat simen kecuali kumpulan alkil balida C-F. Hasil daripada perbandingan, didapati terdapat perbezaan ikatan bidrogen yang berkeamatan kuat dan lebar dalam alkohol pada frekuensi 2842cm⁻¹. Mod pembengkokan bagi kumpulan alkana (CH3) dengan keamatan sederhana banya terdapat dalam cat kayu dengan frekuensi 1452cm⁻¹ dan alkil halida C-F yang hanya wujud dalam larutan cat simen pada frekuensi 1007.47cm⁻¹ juga memperlihatkan perbezaan antara kedua-dua cat ini. Persamaan antara kedua-dua eat ialah mempunyai asid karboksilik yang berkeamatan kuat dan berbentuk lebar dengan regangan C-O serta alkana yang mempunyai getaran regangan simetri dan asimetri bagi metilena (CH2) berkeamatan tinggi pada frekuensi 2919.5cm⁻¹ dan 2850.28cm⁻¹.

Research Journal of Applied Sciences, 2014

Higher penalties may apply, and higher damages may be awarded, for offences and infringements inv... more Higher penalties may apply, and higher damages may be awarded, for offences and infringements involving the conversion of material into digital or electronic form. Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong. represent the views of the University of Wollongong. Recommended Citation Recommended Citation Sulaiman, Samsiah, Crystallographic relationships in copper-aluminium-nickel shape memory alloys, Master of Engineering (Hons.

This investigation is concerned with the characterisation of actual welded samples of P91-a 9%Cr ... more This investigation is concerned with the characterisation of actual welded samples of P91-a 9%Cr heat resisting steel that is widely used for pressure vessels in the power generation industry. Although the creep resistance of the normalised and tempered base steel is excellent, weld fabrication compromises creep performance because of degraded properties in the heat affected zone (HAZ). In order to elucidate the structure and properties of the HAZ, dilatometer heat treatments and simulations of HAZ sub-zones were carried out using both a dilatometer and a Gleeble thermo-mechanical simulator. The simulated samples were used to study the microstructure of the HAZ sub-zones and to subject them to creep testing. In actual welding, post weld heat treatment (PWHT) is used to produce a uniform tempered martensite structure across the weldment, making it difficult to distinguish the HAZ sub-zones and the boundary with the unaffected base plate. Nevertheless, hardness profiles across the HAZ and measurements within the sub-zones confirmed that softening occurs below the base plate hardness after PWHT in the intercritical (IC) and grain refined (GR) sub-zones. The creep fracture times of cross-weld creep samples were also lower than parent metal because of type IV fracture in these HAZ sub-zones. Dilatometric investigations shed new light on the sensitivity of the properties of the martensite to the thermal cycle associated with austenitisation and subsequent cooling. The A C1 and A C3 temperatures were increased with increasing heating rate and M S was lower for a lower heating rate. M S was found to vary from 420°C to 370°C and the hardness of the martensite from 365 to 480 HV, depending on the thermal cycle. This varialibilty is due to the extent of carbide solution. There was a marked increase in hardness with increasing peak temperature of the thermal cycle, but subsequent simulated PWHT substantially decreased the hardness and the hardness range of the simulated sub-zones. An excellent correlation was found between the structures and properties of the HAZ of the actual welds and the simulated sub-zones produced by both dilatometric and Gleeble v techniques. It was established that the heat input (1.6 or 2.6 kJ/mm) had only a minor effect on the microstructure and hardness of Gleeble simulated sub-zone samples. TEM results confirmed the presence of coarse Cr-rich, M 23 C 6 and fine V-and Nb-rich, MC in all simulated sub-zones, before and after PWHT, except for the as simulated GCHAZ in which carbide solution occurred. Accelerated creep testing showed rapid creep failure of both AR and simulated IC and GR sub-zone samples for testing at higher temperatures in the range of 630°C to 670°C and at a higher stress, 100 MPa compared to 80 MPa. Failure was associated with high creep ductility and the phenomenon of rehardening in the region adjacent to the neck due to rapid work hardening prior to fracture. This type of failure has been labelled Mode 1 and is characterised structurally by grains and creep cavities that are strongly elongated parallel to the tensile axis. Another characteristic type of creep failure, Mode 2, exhibits a low creep ductility and transversely aligned creep cavities. This mode was found in notched AR samples and notched simulated GCHAZ samples tested at 630°C and a stress at 80 MPa. However, for both Mode 1 and 2 failures, non-metallic inclusions were found to play a significant role in the nucleation of creep cracking and cavition. The research work identified that the GRHAZ is the most creep susceptible HAZ sub-zone because the thermal cycle results in carbide coarsening, reduced precipitation and solid solution strengthening and a high γ prior grain boundary surface area/unit volume. The creep resistance was most marked for the simulated GCHAZ samples and this property relates strongly to the hardness of the P91 steel prior to creep testing. The important role of non-metallic inclusions in the nucleation of creep cracking and cavitation indicates that control of the type, size distribution and content of inclusions should have a significant effect on the creep life of P91 steel. vi TABLE OF CONTENTS vii ACKNOWLEDGMENTS iii ABSTRACT iv LIST OF FIGURES xiii LIST OF TABLES xxxi TABLE OF CONTENTS vii PART A-INTRODUCTION AND LITERATURE REVIEW 1 CHAPTER 1 INTRODUCTION 3 CHAPTER 2 LITERATURE REVIEW 7 2.1 MATERIALS FOR ELEVATED TEMPERATURE 8 2.1.1 Introduction 8 2.1.2 Alloy Design 2.1.3 Effect of Alloying Elements on Modified 9%Cr-1%Mo Ferritic Steel Chromium Molybdenum, Tungsten and Rhenium Vanadium, Niobium and Titanium Carbon and Nitrogen Boron Manganese and Silicon Nickel, Copper and Cobalt Sulphur and Phosphorus 2.1.4 Continuous Cooling Transformation (CCT) Diagram 2.1.4.1 The metallographic method 2.1.4.2 Thermal arrest method 2.1.4.3 Dilatometry method 2.1.4.3.1 Advantages of dilatometry 2.1.

Thermal simulation has been used to investigate the structure and hardness of the sub-zones of th... more Thermal simulation has been used to investigate the structure and hardness of the sub-zones of the heat affected zone (HAZ) in welded P91 creep resisting steel. Microstructures corresponding to the sub-zones of the HAZ of actual welds were produced using a dilatometer. By simulation, the microstructure of each major sub-zone was reproduced in relatively large volumes compared with the corresponding sub-zone of the HAZ in an actual weldment. A simulated post-weld heat treatment (PWHT) was then imposed to gauge the effect on the structure and properties of the simulated sub-zones of the HAZ. Microstructural analysis and hardness testing confirmed that increasing peak temperature resulted in increases in the solution of alloy carbides, the mean austenite grain size and the hardness after cooling. Subsequent simulated PWHT served to re-precipitate carbide and to significantly reduce the hardness of the HAZ sub-zones.

Research Journal of Applied Sciences, 2014

Thermal simulation has been used to investigate the structure and hardness of the subzones of the... more Thermal simulation has been used to investigate the structure and hardness of the subzones of the heat affected zone (HAZ) in welded P91 creep resisting steel. Microstructures corresponding to the sub-zones of the HAZ of actual welds were produced using a dilatometer. By simulation, the microstructure of each major subzone was reproduced in relatively large volumes compared with the corresponding subzone of the HAZ in an actual weldment. A simulated post-weld heat treatment (PWHT) was then imposed to gauge the effect on the structure and properties of the simulated sub-zones of the HAZ. Microstructural analysis and hardness testing confirmed that increasing peak temperature resulted in increases in the solution of alloy carbides, the mean austenite grain size and the hardness after cooling. Subsequent simulated PWHT served to re-precipitate carbide and to significantly reduce the hardness of the HAZ subzones.

Thermal simulation has been used to investigate the structure and hardness of the sub- zones of t... more Thermal simulation has been used to investigate the structure and hardness of the sub- zones of the heat affected zone (HAZ) in welded P91 creep resisting steel. Microstructures corresponding to the sub-zones of the HAZ of actual welds were produced using a dilatometer. By simulation, the microstructure of each major sub- zone was reproduced in relatively large volumes compared with the corresponding sub- zone of the HAZ in an actual weldment. A simulated post-weld heat treatment (PWHT) was then imposed to gauge the effect on the structure and properties of the simulated sub-zones of the HAZ. Microstructural analysis and hardness testing confirmed that increasing peak temperature resulted in increases in the solution of alloy carbides, the mean austenite grain size and the hardness after cooling. Subsequent simulated PWHT served to re-precipitate carbide and to significantly reduce the hardness of the HAZ sub- zones.

University of Wollongong Thesis Collection, 2007

Research Journal of Applied Sciences, 2014

University of Wollongong Thesis Collection, 2007